Name: Imran HozaSchool: Helena Jones Robinson High SchoolCandidate Id: School Centre Number:Title: What are the different erosional and depositional features found along the North and East Coast of Grand Turk, Turks and Caicos Islands and how are they formed?

3/4/2014

Table of ContentsContentsPageAim of Study1Maps Showing Location of Study Area2Methodology4Presentation and Analysis of Data5Conclusion11Bibliography12

Aim of StudyTo identify the erosional and depositional features found along the North and East coast of Grand Turk, Turks and Caicos Islands, and to describe the factors that lead to their formations.

MethodologyOn the first of November 2013 during the period of 9:30 am -2:30 pm a group of seven students began and completed a study of three of the coast of Grand Turk which was:1. The North Coast2. The East Coast3. The West CoastThe students went out to identify the erosional features, depositional features and other various features found in the study areas. When a certain feature was identified it was marked off the checklist. A compass was used to determine the direction of the wind at each study area. The students then divided into three groups to perform the following tasks at each coast: The first group of students use range poles and measuring tapes to determine the height of the waves. The range pole was placed vertically in the water as the wave approached, the students marked out the crest and trough of the waves. They then measured the distance between the two markings to determine the wave height. The student also determined the frequency of the waves by the use of a stopwatch and by counting the number of waves that crashed on the shore every minute for a five minute interval. The second group took photographs and sketches of the study areas and their various features. . Also they carried out an experiment to find out what material the cliff was composed of by placing a sample of the cliff into a beaker and pouring hydrochloric acid over it. The third group went out with the use of a tape measure to measure the height/length of the measurable features such as the beach, and the cliff. They also took a note of everything that occurred at each of the study areas.The data collected from the three groups were shared among the students. The students also collected information from internet sites and geography text books. Before the field trip was over, the students collected samples of: pebbles, beach sand, and other material found in their areas of study for classification

Presentation and Analysis of DataThe Turks and Caicos Islands are a group of islands located in the Bahamian archipelago in the Caribbean. They are mostly composed of limestone rock. The size of the Turks and Caicos Islands is 193 sq. miles. The capital of the Turks and Caicos Islands is Cockburn Town which is located on the island of Grand Turk. The aim of this SBA is to identify the erosional and depositional features found along the North and East coast of Grand Turk, Turks and Caicos Islands, and to describe the factors that lead to their formations.At the north coast, a cliff, wave-cut platform, stack, a small beach and cave with a blow hole were the coastal features identified. These features were mainly formed by the action of waves pounding against the coast line. The cliff and wave-cut platform are clearly illustrated in the photograph below.Plate 1 Photograph showing the cliff and wave-cut platform at the North Coast

CliffWave-cut Platform

Cliffs are steep, often near-vertical slopes that rise abruptly from the sea (Ottley and Gentles, 2006). The height of the cliff was found to be 30ft. The test that was carried out indicated that the cliff was made of limestone that contained calcium carbonate which is easily weathered. Therefore it was deduced that the cliff was formed as a result of the following processes: Hydraulic Action - The sheer force of the waves as they break against a cliff causing broken rock fragments to be dislodged (Clarke et al, 2012). At the North Coast it was observed that large broken rock fractures were found at/near the base of the cliff and it was deduced that they, along with the cliff were formed due to this process. Abrasion - Pebbles are picked up by the sea and flung against the cliff (Clarke, Hutton, Nurse, Rocke and Ross, 2012). The large amount of pebbles found all around the North Coast were inferred to have been brought about as a result of this process. Solution - The chemical decomposition of limestone rocks by sea water (Ottley and Gentles, 2006). As previously stated the cliff was composed of limestone therefore this process will affect it greatly.The other feature shown in Plate 1 above was a wave-cut platform. A wave-cut platform is a narrow flat area that is often found at the base of a sea cliff (Wikipedia, 2013). It was formed as a result of wave action affecting the base of the cliff and undercutting it. After a while the top of the cliff collapses and the cliff face retreats leaving the wave-cut platform. It was observed that the wave-cut platform that was created by wave erosion mainly in the form of hydraulic action, had cracks, joints and a white-brownish appearance, all indicating that it was also made of limestone.It was also observed that due to the fact that there were areas of reddish-brown colouring on the cliff and the wave- cut platform, the chemical weathering process of oxidation was impacting their formation.Under the cliff, there was a small sea cave which had a blow-hole on its roof. It is illustrated in Plate 2. A sea cave is cave formed in a cliff by wave action of an ocean or lake (Britannica, 2014). It was hypothesized that this cave was formed by the processes of hydraulic and abrasion because of the type and size of rocks found in the cave.

Plate 2 Photograph showing the sea cave found at the North Coast

Small Sea CaveLight rays showing location of blow hole There was a collapsed stack that was seen near the cave. Wave pounding (Hydraulic Action) was the factor that leads to the formation of this feature as the waves were seen to be constantly pounding it and attacking the lines of weaknesses in it and eroding it(see plate 3). Overtime, this stack maybe further be eroded to form a stump.Plate 3 - Photograph showing a stack at the North Coast

Waves constantly pounding on stackStackThe height of the waves was found to be 7.03 inches. Along with the height, the frequency of these waves over a five minute interval was used to determine the type of wave affecting this coast at the time of study. The results of the frequency of these waves were recorded in Table 1.

Table 1 Table showing the frequency of the waves at the North Coast over a five minute interval.MinuteNumber of Waves

1st9

2nd8

3rd9

4th8

5th9

These measurements helped to prove that the type of wave affecting the North Coast at that time was constructive waves. This mainly explained why there was a small beach at this coast which was inferred to be formed as a result of these waves carrying fine materials, such as sand and shingle, onto the shore and depositing them. The rate of erosion was slowed down due to the weak backwash of the waves and this allowed the sediments to build up overtime to create this beach. A beach is a deposit of sand and/or pebbles found at the coast. (Clarke et al, 2012).

At the east coast there were both depositional and erosional features. A beach, cliff and cave were identifiedFigure 1 Sketch Map of the East Coast

Plate 4 Photograph showing the cave at the East Coast

CliffSmall CaveDue to the fact that the cliff and the cave were situated a few feet away from the sea, as shown in the Figure 1 above, it was deduced that these features were formed during stormy conditions which brought with them high storm tides that consisted of destructive waves that are able to erode the cliff and its base through the process of wave pounding. The height of this cliff was found to be 16 feet and 4 inches.Plate 5 Photograph showing the beach at the East Coast

This beach was composed of very fine sediments (sand). Upon observation, the sediments had a muddy appearance which indicated that the process of suspension, a transportation process was taking place at this time. This built up of sediments is what created the gentle sloping beach. At the time of the observation no waves were observed, however due to the presence of a light breeze, small ripples were observed. It was deduced that this was a low energy coast. This helped to explain the existence of this gentle sloping beach which had a length of over 2,000 feet and a width of 60 feet. It was deduced that this beach was created during a time when there was constructive waves which brought them fine sediments, such as sand, that were deposited there.

Conclusion Wave action caused the formation of all the coastal features found at each of the coasts. There were both erosional and depositional features found along each of the coast. In the North Coast there was a cliff, wave-cut platform, small beach, stack and a cave, most of which were formed by wave erosional process of hydraulic action, abrasion and solution. The small beach was formed by deposition of sand due to the constructive wave nature of the area. This was also the cause of other materials such as pebbles and shells being deposited there. In the East Coast there was a cliff and a cave which were also formed by wave erosion. There was also a large, low energy, gentle sloping beach at this coast that was assumed to have formed during a period where constructive waves were present at this coast.

BibliographyClarke, Hutton, Nurse, Rocke and Ross Geography for CSEC, Nelson Thornes, 2012Ottley and Gentles Geography for CSEC, Longman, 2006 http://en.wikipedia.org, Wave-cut Platform, 2013http://www.britannica.com, Sea Cave, 2014